Balloon Mitral Valvuloplasty in Second Trimester Pregnancy with Severe Mitral Stenosis
Percutaneous balloon mitral valvuloplasty (BMV) should be performed in a second trimester pregnant patient with severe mitral stenosis only if she remains symptomatic with NYHA class III-IV heart failure symptoms despite optimal medical therapy with beta-blockers and diuretics. 1, 2
Initial Medical Management
Before considering BMV, aggressive medical therapy must be attempted:
- Beta-blockers are the first-line medical therapy for rate control and reducing the transvalvular gradient in pregnant patients with severe mitral stenosis 2
- Diuretics should be added for symptomatic relief if pulmonary congestion develops 1
- Bed rest may provide additional symptomatic benefit 1
The patient should be managed in a tertiary care center with a dedicated Heart Valve Team including cardiologists, cardiac surgeons, anesthesiologists, and high-risk obstetricians 1, 2
Indications for BMV During Pregnancy
BMV is indicated only when:
- Severe mitral stenosis is present (mitral valve area ≤1.5 cm²) 1, 2
- Patient has persistent NYHA class III-IV symptoms despite medical therapy 1
- Valve morphology is favorable for the procedure (minimal calcification, good leaflet mobility, minimal subvalvular disease) 1
BMV is NOT recommended prophylactically or in patients with severe mitral stenosis who have good functional tolerance without pulmonary hypertension 1
Procedural Considerations
Timing
- Preferably perform after 20 weeks of gestation, which is the safest period for the fetus 1
- The second trimester is generally preferred when intervention is needed 3, 4
Technical Requirements
- Must be performed only in highly experienced centers with operators who have demonstrated low complication rates 1
- The Inoue balloon technique is particularly advantageous as it keeps the procedure as short as possible 1, 5
- Radiation exposure must be minimized by abdominal shielding and omitting hemodynamic measurements and angiography when possible 1, 5
- Continuous fetal monitoring should be performed throughout the procedure 1
- Backup cardiac surgery, anesthesiology, and high-risk obstetrics services must be immediately available 1
Expected Outcomes and Risks
Maternal Benefits
- Mitral valve area typically increases from approximately 0.8-0.9 cm² to 1.6-1.7 cm² 3, 6, 5
- Marked symptomatic improvement with return to NYHA class I-II 3, 6
- Significant reduction in pulmonary artery pressures and transvalvular gradients 3, 4
Procedural Risks
- 5% risk of severe traumatic mitral regurgitation requiring emergency surgery under cardiopulmonary bypass, which is particularly dangerous for the fetus 1
- Very low risk of cardiac tamponade or embolic events 1
- Fluoroscopy time is typically 7-8 minutes with appropriate technique 5
Fetal Outcomes
- Excellent fetal outcomes when performed by experienced operators with appropriate radiation shielding 3, 5
- Normal delivery rates are high with healthy newborns 6, 5
Critical Pitfall to Avoid
Open heart surgery during pregnancy carries a 30-40% fetal mortality rate and up to 9% maternal mortality rate 1. Surgery should be reserved only for patients with:
- Refractory NYHA class IV symptoms unresponsive to medical therapy AND
- Unfavorable valve morphology making BMV too high-risk 1
If surgery becomes necessary, it should be performed with high pump flows, normothermic perfusion, shortest possible pump time, and continuous fetal monitoring 1
Alternative Management for Unfavorable Anatomy
For patients with severe leaflet calcification, thickening, immobility, or commissural calcification who have refractory NYHA class IV symptoms, mitral valve replacement under controlled surgical conditions may be safer than attempting high-risk BMV 1. However, this carries the significant fetal and maternal mortality risks noted above and should only be considered when the mother's life is threatened 1